Conventionally, a positioning control apparatus controlling a feed device is mounted on a device in which a highly accurate positioning control is required, such as a machine tool and a mounter. A common feed device on a machine tool is configured with a guide mechanism for guiding a moving body and a drive mechanism for moving the moving body, and the operation of the drive mechanism is controlled by a positioning control apparatus.
As for the guide mechanism, there can be mentioned, for example, a configuration comprising a slide guide mechanism or a rolling guide mechanism, and as for the drive mechanism, there can be mentioned, for example, a configuration comprising a ball screw, a nut which is screwed onto the ball screw and is fixed on the moving body and a drive motor for rotating the ball screw about its axis to move the moving body in the axial direction of the ball screw.
The positioning control apparatus generates a control signal on the basis of a target moving position of the moving body, and transmits a drive current based on the generated control signal to the drive motor to thereby drive the drive motor. Thereby, the ball screw is rotated about its axis and the moving body is moved to the target moving position.
On such a positioning control apparatus, conventionally, in order to compensate for a tracking error generated between a target moving position and an actual moving position of the moving body, the so-called feedback control is generally used in which the rotational speed of the drive motor, the rotational position of the drive motor, an actual current transmitted to the drive motor and so on are monitored and controlled. As a positioning control apparatus performing a high degree of feedback control, a position controller as disclosed in the Japanese Patent No. 4014162 has been suggested.
This position controller is configured to perform a common feedback control on the basis of the rotational position and the rotational speed of the drive motor and feed back to the control signal an integrated feedback value based on a function which four kinds of information, namely the speed of the moving body, the position of the moving body, the rotational speed of the drive motor and the rotational position of the drive motor, concern, thereby compensating for a tracking error generated in the feed drive system.